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Editor for this issue: Helen Dry <hdryemunix.emich.edu>
quijote.lang.usf.edu>The following books are available for review in the "Language Quarterly." Aaron Halpern, "On the Placement and Morphology of Clitics." Bruce hayes, "Metrical Stress Theory: Principles and Case Studies." Makoto Kanazawa and Christopher J. Pinon, "Dynamics, Polarity and Quantification." Young-Key Kim-Renaud, "Theoretical Issues in Korean Linguistics." R. E. Batchelor, "Using Spanish Synonyms." If you would like to review any of these books, please contact me by e-mail at <adderleyMail to author|Respond to list|Read more issues|LINGUIST home page|Top of issue
central.cis.upenn.edu>The following new technical reports are now available from the Institute for Research in Cognitive Science: Centering: A Framework for Modelling the Local Coherence of Discourse Barbara J. Grosz Aravind K. Joshi Scott Weinstein IRCS-95-01 $2.40 Our original paper (Grosz, Joshi, and Weinstein, 1983) on centering claimed that certain entities mentioned in an utterance were more central than others and that this property imposed constraints on a speaker's use of different types of referring expressions. Centering was proposed as a model that accounted for this phenomenon. We argued that the coherence of discourse was affected by the compatibility between centering properties of an utterance and choice of referring expression. Subsequently, we revised and expanded the ideas presented therein. We defined various centering constructs and proposed two centering rules in terms of these constructs. A draft manuscript describing this elaborated centering framework and presenting some initial theoretical claims has been in wide circulation since 1986. This draft (Grosz, Joshi, and Weinstein 1986, hereafter, GJW86) has led to a number of papers by others on this topic and has been extensively cited, but has never been published. We have been urged to publish the more detailed description of the centering framework and theory proposed in GJW86 so that an official version would be archivally available. The task of completing and revising this draft became more daunting as time passed and more and more papers appeared on centering. Many of these papers proposed extensions to or revisions of the theory and attempted to answer questions posed in GJW86. It has become ever more clear that it would be useful to have a "definitive" statement of the original motivations for centering, the basic definitions underlying the centering framework, and the original theoretical claims. This paper attempts to meet that need. To accomplish this goal, we have chosen to remove descriptions of many open research questions posed in GJW86 as well as solutions that were only partially developed. We have also greatly shortened the discussion of criteria for and constraints on a possible semantic theory as a foundation for this work. A First-Order Axiomatization of the Theory of Finite Trees Rolf Backofen James Rogers K. Vijay-Shanker IRCS-95-02 $3.29 We provide first-order axioms for the theories of finite trees with bounded branching and finite trees with arbitrary (finite) branching. The signature is chosen to express, in a natural way, those properties of trees most relevant to linguistic theories. These axioms provide a foundation for results in linguistics that are based on reasoning formally about such properties. We include some observations on the expressive power of these theories relative to traditional language complexity classes. A Lexicalized Tree Adjoining Grammar for English The XTAG Research Group IRCS-95-03 $11.75 This document describes a sizable grammar of English written in the TAG formalism and implemented for use with the XTAG system. This report and the grammar described herein supersedes the TAG grammar described in [Abeilli et al., 1990]. The English grammar described in this report is based on the TAG formalism developed in [Joshi et al., 1975], which has been extended to include lexicalization ([Schabes et al., 1988]), and unification-based feature structures ([Vijay-Shanker and Joshi, 1991]). The grammar discussed in this report extends the grammar presented in [Abeilli et al., 1990] in at least two ways. First, this grammar has more detailed linguistic analyses, and second, the grammar presented in this paper is fully implemented. The range of syntactic phenomena that can be handled is large and includes auxiliaries (including inversion), copula, raising and small clause constructions, topicalization, relative clauses, infinitives, gerunds, passives, adjuncts, it-clefts, wh-clefts, PRO constructions, noun-noun modifications, extraposition, determiner phrases, genitives, negation, noun-verb contractions, sentential adjuncts and imperatives. The XTAG grammar has been relatively stable since November 1993, although new analyses are still being added periodically. Preservation Theorems in Finite Model Theory Eric Rosen Scott Weinstein IRCS-95-04 $2.25 We develop various aspects of a finite model theory. We establish the optimality of normal forms over the class of finite structures and demonstrate separations among descriptive complexity classes. We establish negative results concerning preservation theorems. We introduce a generalized notion of preservation theorem and establish some positive results concerning "generalized preservation theorems" for first-order definable classes of finite structures which are closed under extensions. CLiFF Notes Research in the Language, Information and Computation Laboratory of the University of Pennsylvania Annual Report 1994, Vol. 4 Matthew Stone and Libby Levison (eds.) IRCS-95-05 MS-CIS-95-07 $9.35 This report takes its name from the Computational Linguistics Feedback Forum (CLiFF), an informal discussion group for students and faculty. However the scope of the research covered in this report is broader than the title might suggest: this is the yearly report of the LINC Lab, the Language, Information and Computation Laboratory of the University of Pennsylvania. It may at first be hard to see the threads that bind together the work presented here, work by faculty, graduate students and postdocs in the Computer Science and Linguistics Departments, and the Institute for Research in Cognitive Science. It includes prototypical Natural Language fields such as: Combinatorial Categorial Grammars, Tree Adjoining Grammars, syntactic parsing and the syntax-semantics interface; but it extends to statistical methods, plan inference, instruction understanding, intonation, causal reasoning, free word order languages, geometric reasoning, medical informatics, connectionism, and language acquisition. Naturally, this introduction cannot spell out all the connections between these abstracts: we invite you to explore them on your own. In fact, with this issue it's easier than ever to do so: this document is accessible on the "information superhighway". Just call up http://www.cis.upenn.edu/~cliff-group/94/cliffnotes.html In addition, you can find many of the papers referenced in the CLiFF Notes on the net. Most can be obtained by following links from the authors' abstracts in the web version of this report. The abstracts describe the researchers' many areas of investigation, explain their shared concerns, and present some interesting work in the Cognitive Science. We hope its new online format makes the CLiFF notes a more useful and interesting guide to Computational Linguistics activity at Penn. **************************************************************************** The reports are available in bound form for the price listed above, or may be obtained for free, electronically. To obtain a compressed postscript copy of the report, open an anonymous ftp session on ftp.cis.upenn.edu path: pub/ircs/technical-reports The files are named according to their number. For example, Report 95-01 is stored as 95-01.ps.Z, 95-02 is stored as 95-02.ps.Z, etc. If you are using ftp, change the setting to binary and download the file. To get a copy of Report 95-01, you would type: binary get 95-01.ps.Z You can also obtain files through electronic mail. Send a mail message to ircsservMail to author|Respond to list|Read more issues|LINGUIST home page|Top of issue